Dentists and hygienists have used prophylaxis (prophy) angles for over 100 years to clean and polish teeth. Until recently, prophy angles were made of metal so they could be used over and over again, one patient after the next. To prevent the spread of infectious diseases from patient to patient, the dentist or hygienist cleaned and sterilized the angle after each use.
In recent years, a market has developed for disposable prophy angles due in part to increased awareness and concern for the spread of infectious diseases such as hepatitis and AIDS. Since disposable prophy angles are discarded after each use, they must be produced in extraordinarily greater quantities than the metal angles they have replaced. As a result, a need exists to develop cost-effective processes for manufacturing disposable prophy angles in large quantities.
There are three basic steps in the production of disposable prophy angles: the manufacture of the components of the angle, the assembly of the angle components, and the packaging of the assembled angles. The packaging step can be further subdivided into individual bagging, batch counting, and carton sealing.
The manufacture of individual angle components and the bagging of assembled angles are traditionally performed by automated machinery since this is the most cost-effective means currently available for mass production and the machinery to perform these functions is available due to the fact that a multitude of products are manufactured and packaged in a manner similar to disposable prophy angles. The assembly step, however, is done largely by hand since automated machinery for prophy angle assembly is not readily available. Such equipment must be designed specifically for this. The batch-counting step is also performed largely by hand since this equipment must also be designed specifically for this purpose and because, to be practical, it must be integrated with other automated machinery. Carton sealing equipment, although readily available, must also be integrated with other automated machinery in order to be practical.
While the assembly of prophy angles by hand has the advantage of requiring minimal initial investment; it has several inherent disadvantages. Lubrication on the bearings and gears of disposable prophy angles provides smoother operation and increased life. Yet, when done by hand, this step can be somewhat difficult and add a significant amount of time, and therefore cost, to the assembly operation. Controlling the amount of lubricant applied in hand assembly can also be difficult. An angle that is under-lubricated may run less smoothly or overheat when used. Lubricant may leak out of an over-lubricated angle making it messy for the end user, and ultimately the patient in whose mouth the device will be used.
Another disadvantage is the variability in quality of the finished product. Due to the repetitious nature of assembly by hand, it is often difficult for assembly personnel to remain focused on their work. For this reason, along with the fact that large numbers of assembly personnel are required, variability in the quality of the finished product, especially related to the application of lubricant is a constant problem.
All of the disadvantages above add to the cost of hand-assembled disposable prophy angles in order to ensure that they are clean, safe, and high quality.